AttributeError: 'NoneType' object has no attribute 'render'

[vikumarks]

Test Script failed with error "AttributeError: 'NoneType' object has no attribute 'render'"
sanity/test_switch_reload.py::test_switch_reload_all
sanity/test_check_links.py::test_check_and_validate_switch_links
sanity/test_switch_reload.py::test_switch_reload_one_switch

    async def test_check_and_validate_switch_links(testbed):
        """
        Test Name: test_check_and_validate_switch_links
        Test Suite: suite_system_health
        Test Overview: Check the links between infra, agg, oob, dist devices if they are UP
        Test Procedure:
          1. get all the reachable devices
          2. check the operstate of the link enumerated in device.links
          3. fail the test if any of the link operstate is DOWN
        """
        # check the links
>       await check_and_validate_switch_links(testbed)

/usr/local/lib/python3.10/dist-packages/dent_os_testbed/test/test_suite/sanity/test_check_links.py:109: 

>       self.html = template.render(height=height,
                                    width=width,
                                    nodes=nodes,
                                    edges=edges,
                                    heading=heading,
                                    options=options,
                                    physics_enabled=physics_enabled,
                                    use_DOT=self.use_DOT,
                                    dot_lang=self.dot_lang,
                                    widget=self.widget,
                                    bgcolor=self.bgcolor,
                                    conf=self.conf,
                                    tooltip_link=use_link_template,
                                    neighborhood_highlight=self.neighborhood_highlight,
                                    select_menu=self.select_menu,
                                    filter_menu=self.filter_menu,
                                    notebook=notebook,
                                    cdn_resources=self.cdn_resources
                                    )
E       AttributeError: 'NoneType' object has no attribute 'render'

/usr/local/lib/python3.10/dist-packages/pyvis/network.py:479: AttributeError

[muchetan]

create a PR #219